Most agricultural plant had a "Lucas key" [1] which meant you could use any key to start any machine.

I used to have one on my house keys long after I actually needed it, kind of an agricultural/industrial shibboleth. It's also how many many years ago I came to be drink-driving an eight tonne excavator through streets of Glasgow at 3am, with some rather grateful Strathclyde Police traffic cops keeping my way clear, but that's a whole 'nother story.